Method for transmitting packet-oriented information via a time-division-multiplex-oriented radio link

ABSTRACT

A method for transmitting packet-oriented information via a time division multiplex oriented radio link, wherein, in the downstream direction of transmission, the transmission channels are permanently allocated to all communication terminals. The packet-oriented information to be transmitted is inserted into frame-relay-oriented transmission packets, including a destination address and broadcast to all communication terminals via the permanently allocated transmission channels. The transmission packets broadcast are received by the communication terminals having the allocated destination addresses and are forwarded.

1. Field of the Invention

The present invention relates to a method for transmittingpacket-oriented information via a time division multiplex oriented radiolink wherein, in particular, the resources of the radio link, or itstransmission channels, are used in a more efficient manner.

2. Description of the Prior Art

Feeder networks of communication networks, such as public or privatecommunication networks, are frequently connected to communicationterminals with packet-oriented information transmission, for example,personal computers with an Internet function. The communicationterminals are increasingly wirelessly connected, i.e. by a radio link,to the feeder network, the communication terminal being connected bywires to a terminating device implementing the radio link at thecommunication terminal end. At the feeder network end, the radio link isimplemented by a base station which is connected in most cases to afeeder network access device by further optical or coaxial or coppertransmission links. The feeder network access device which partiallyhandles the control of the radio links is connected, for example, via anISDN-oriented interface, such as an ISDN primary interface S20, directlyor via a public or private communication network to an Internet server.Radio links in the feeder network are currently preferably implementedin accordance with a time-division multiplex access method or TDMAaccess (TDMA) method, respectively particularly in accordance with thestandardized DECT access method, see also ETSI Standard 300 175 Part 1to 9 in this respect.

When a connection setup is initiated by a communication terminal, aphysical connection is set up to the respective Internet server in thecase of an Internet connection directly or with the aid of the switchingfacility in accordance with the dialing information specified during theconnection setup via the radio link and the feeder network. During theconnection setup, a logical connection is installed between thecommunication terminal and Internet server. In the case of an Internetconnection, this logical connection is implemented by a point-to-pointprotocol, called PPP in the technical world, with the aid of which theexchange of Internet packets is controlled. In this arrangement,information packets of different protocols are transported transparentlywith the aid of a higher-level PPP protocol. The connection set up tothe Internet server remains up until the respective connection isreleased by the communication terminal and the connection is cleareddown. Since an Internet connection frequently has phases, e.g. viewingor evaluating transmitted graphics, in which no Internet packets aretransmitted, the resources, especially of the complex radio link, areinefficiently used.

An object of the present invention, therefore, consists in using theresources of the radio link, i.e. its transmission channels, moreefficiently.

SUMMARY OF THE INVENTION

Accordingly, an essential aspect of the method according to the presentinvention can be seen in the fact that in the downstream direction oftransmission, at least some of the transmission channels are permanentlyallocated to all communication terminals and the packet-orientedinformation to be transmitted for the respective communication terminalsis inserted into transmission packets with the aid of a packet-orientedtransmission protocol, a destination address being in each case insertedinto the transmission packets for the respective communicationterminals. The transmission packets are broadcast to all communicationterminals via the permanently allocated transmission channels and thetransmission packets broadcast are received by the communicationterminals having the associated destination addresses and are forwarded.The access protocol is advantageously implemented by a frame relaytransmission method.

An essential advantage of the method according to the present inventioncan be seen in the fact that the radio engineering resources in thedownstream direction can be used to a maximum extent and no change ofthe time-division-multiplex-oriented access method implemented isnecessary in the components implementing the radio link. Thus, anincrease in efficiency of the radio engineering resources occurs withthe least additional expenditure. Another advantage can be seen in thefact that a packet-oriented transmission protocol can be implementedexternally, i.e. not in the components implementing the radio link, theimplementation expenditure being kept low by using the simplehigh-performance frame relay transmission protocol.

The destination addresses can advantageously correspond directly to thecommunication network addresses provided for the communicationterminals, or a destination address being allocated to eachcommunication terminal and when a transmission packet is transmitted,the protocol-oriented destination address is derived from thecommunication-network-specific destination address and inserted into therespective transmission packets. As such, either thecommunication-network-specific destination address already transmittedin the connection setup or a transmission-protocol-specific destinationaddress is derived from the communication-network-specific destinationaddress and used for the destination-oriented transmission of thetransmission packets to the respective communication terminals.

In the upstream direction of transmission, a DECT or a CDMA accessmethod can be advantageously provided, the transmission channels (UPC)being allocated individually for each connection or via a token-orientedmethod TDMA-oriented method, a collision controlled method or atime-table-controlled method. In the upstream direction of transmission,an access method is of advantage in which the radio engineeringresources, i.e. the transmission channels, are allocated to a connectiontemporarily since the allocation would give rise to considerable controlcomplexity if the upstream radio link were to be implemented in abus-like manner.

The number of transmission packets (tp1..tpn) which can be transmittedper unit time is advantageously variable for each connection V.Accordingly, the radio engineering resources can be used to a maximumextent depending on the available resources Ver.

According to an advantageous further development of the method accordingto the present invention, a logical connection is set up from thecommunication terminal to an Internet server and the connection V set upremains permanently. Due to this measure, an E-mail can be transmittedat any time to the communication terminal, especially a personalcomputer having an E-mail function. It is also possible to have a fixedcharged for such a connection since the duration of the call does notneed to be taken into consideration.

Additional features and advantages of the present invention aredescribed in, and will be apparent from, the following DetailedDescription of the Preferred Embodiments and the Drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows in a block diagram a communication arrangement suitable forimplementing the method according to the present invention; and

FIGS. 2 a and 2 b show in a block diagram the structure of thetransmission packets and their insertion into time slots or,respectively, transmission channels of the DECT-oriented downlink radiolink.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows an Internet server IS to which base station controllers BSCare connected via, for example, 2-Mbit/s interfaces, a base stationcontroller BSC is shown by way of example. The base station controllerBSC is connected to a base station BS which represents the centralfacility of a wireless access system DAS. In the wireless access system,the base station BS is connected to terminating facilities RNT via aradio link FS, a terminating facility RNT is shown by way of example inFIG. 1. The wireless access system DAS and the base station controllerBSC together form a feeder network AN. In the terminating facility RNT,a V.24 interface V.24 or, optionally, a USB interface USB is implementedto which a communication terminal KE implemented by a personal computerPC is connected. For the communication terminal KE, for example, anInternet function is provided with the aid of which Internet-oriented,packet-oriented information pi is formed and transmitted to the Internetserver IS and received from the latter.

Packet-oriented information pi is formed in accordance with the knownInternet protocol 4 or 6 also known as IP 4 or IP 6 in the technicalfield, i.e. the Internet packets exhibit the respective Internetaddresses ia1..ian in the header. Packet-oriented information pi1..pinor Internet packets formed in this manners see also FIG. 2 a, aretransmitted by the Internet server IS to the base station controller BSCfor the personal computers PC connected to the wireless access systemDAS, and in the base station controller the packet-oriented informationpi is inserted into transmission packets tp which are formed inaccordance with the frame relay transmission method. A transmissionpacket tp according to the frame relay transmission method consists of astart bit combination, a header field, a message field, a checkinformation item for the header field and an end bit combination, nodata protection information being formed and inserted for the messageinformation. The frame relay transmission method is used, in particular,in the transmission of packet-oriented, transaction-oriented data. Assuch, it can be used particularly advantageously for the transmission ofpacket-oriented, transaction-oriented Internet packets. Into the headerof the transmission packets tp1..tpn, corresponding destinationaddresses za1..zan are inserted in the base station controller BSC, adestination address za1..zan being allocated to each communicationterminal KE. In each case, the destination address za of the terminatingfacilities RNT or communication terminals (KE) to which thepacket-oriented information pi contained therein is to be transmitted isinserted into the transmission packets tp1..tpn.

The radio link FS is divided into upstream and downstream transmissionchannels UPC, DOC. When the radio link FS is implemented in accordancewith the standardized DECT access method, 12 upstream and 12 downstreamtransmission channels UPC, DOC are available in the case of onefrequency band. In the case of a number of frequency bands,correspondingly more upstream and downstream transmission channels UPC,DOC are available. According to the present invention, all or a largeproportion of the available downstream transmission channels DOC, anasymmetric distribution of upstream and downstream transmission channelscan also be provided, are permanently allocated to all terminatingfacilities RNT or communication terminals KE for transmittinginformation. As such, for example, a transmission capacity of 12×32kbit/s is available in the case of one DECT frequency band. During aconnection setup initiated by the communication terminal KE, a virtualconnection V is set up from the communication terminal KE via the radiolink FS to the base station controller BSC. During the connection setup,a connection is also set up to the Internet server IS and bothconnections can remain permanently. As an alternative, in the case of animplementation of the frame relay transmission method up to the Internetserver IS, the logical connection V can be set up to the Internet serverIS and remain permanently. This provides the advantage thatpacket-oriented information pi—especially E-mail information—can betransmitted at any desired time, especially in the downstream directionof transmission.

The transmission packets tp1..tpn formed, including the inserteddestination addresses za1..zan, are transmitted to all terminatingfacilities RNT via the downstream transmission channels DOC.Transmission packets tpx, tpy formed are transmitted, for example, at atransmission rate of 64 kbit/s in “free double-slot channels” of thedownstream transmission channels DOC1..DOC12, see also FIG. 2 b. In theterminating facilities RNT, the transmitted transmission packetstp1..tpn are received, and the destination address tp1..tpn insertedinto the header is investigated, in all allocated downstreamtransmission channels DOC1..DOC12. If the inserted destination occursza1..zan corresponds to the destination address za1..zan allocated tothe respective terminating facility RNT or to the communication terminalKE, the associated transmission packet tp1..tpn is received in therelevant terminating facility RNT and forwarded to the personal computerPC.

In the upstream transmission channels UPC, which is not shown in detail,arbitrary access methods can be used for the access by the terminatingfacilities RNT to the radio engineering resources of the upstreamdirection of transmission. Possible access methods are the DECT accessmethod already specified or the CDMA method. Furthermore, the tokenaccess methods or access methods with collusion detection ortime-table-controlled methods, provided for accessing local areanetworks, can be used or provided.

The use of the method according to the present invention is notrestricted to the exemplary embodiment and can be used in other feedernetwork configurations including a number of radio links FS or a numberof feeder network components; only the destination addresses za need tobe converted or adapted in the case of different access and switchingmethods.

Although the present invention has been described with reference tospecific embodiments, those of skill in the art will recognize thatchanges may be made thereto without departing from the spirit and scopeof the invention as set forth in the hereafter appended claims.

1. A method for transmitting packet-oriented information between acentral facility and communication terminals via a feeder network, atleast one radio link including transmission channels implemented inaccordance with a TDMA access method being arranged in a communicationterminal area in the feeder network, the method comprising the steps of:permanently allocating, in a downstream direction of transmission, atleast some of the transmission channels to all communication terminals;inserting the packet-oriented information to be transmitted for therespective communication terminals into transmission packets using apacket-oriented transmission protocol; inserting a respectivedestination address into the transmission packets for the respectivecommunication terminals; broadcasting the transmission packets to allthe communication terminals via the permanently allocated transmissionchannels; and receiving the transmission packets, via the downstreamdirection of transmission, by the terminating facilities associated withthe communication terminals having the associated destination addresses,and then forwarding the transmission packets to the communicationterminals.
 2. A method for transmitting packet-oriented informationbetween a central facility and communication terminals via a feedernetwork as claimed in claim 1, wherein the transmission protocol isimplemented via a frame relay transmission method.
 3. A method fortransmitting packet-oriented information between a central facility andcommunication terminals via a feeder network as claimed in claim 1,wherein the destination addresses correspond to the communicationnetwork addresses provided for the communication terminals.
 4. A methodfor transmitting packet-oriented information between a central facilityand communication terminals via a feeder network as claimed in claim 1,wherein a protocol-oriented destination address is allocated to eachcommunication terminal, the protocol-oriented destination addressesbeing derived from the communication-network-specific destinationaddresses and being inserted into the respective transmission packets.5. A method for transmitting packet-oriented information between acentral facility and communication terminals via a feeder network asclaimed in claim 1, wherein, in an upstream direction of transmission,one of a DECT and a CDMA access method is provided, the transmissionchannels being allocated one of individually for each connection, by atoken-oriented method, by a TDMA-oriented method, by acollision-controlled method, and a time-table-controlled method.
 6. Amethod for transmitting packet-oriented information between a centralfacility and communication terminals via a feeder network as claimed inclaim 1, wherein a sum of the transmission packets broadcast over atleast some of the downstream transmission channels per unit time isequal to a sum of all transmission packets transmitted over a framerelay transmission path per unit time.
 7. A method for transmittingpacket-oriented information between a central facility and communicationterminals via a feeder network as claimed in claim 1, wherein a logicalconnection is permanently set up from the communication terminal to thecentral facility.
 8. A method for transmitting packet-orientedinformation between a central facility and communication terminals via afeeder network as claimed in claim 7, wherein a number of transmissionpackets which can be transmitted per unit time is variable for eachlogical connection.